Radio cell performance monitoring and/or control based on user equipment positioning data and radio quality parameters

ABSTRACT

In broadband networks for fixed or cellular mobile radio access using the ETSI/BRAN standard, such as UTRANs, Wi-Fi or WLAN wireless communication networks, continuously monitored user equipment positioning data and radio link parameters indicating quality of service of a wireless link between a base transceiver station located in a mobile radio cell of the wireless cellular network and a mobile terminal connected to and being served by the base transceiver station, such as signal-to-noise-plus-interference ratio, power class and bit error rate in uplink and/or downlink direction of the wireless link, may be used for radio cell performance monitoring and/or control. By tracking current positions of user equipment (UE) served by the network, the network can offer location-based services to the UE. A network management system with an integrated alarm signaling unit and having access to a base transceiver station&#39;s link performance monitoring system and/or location measurement unit may be used.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and hereby claims priority to EuropeanApplication No. 07023184 filed on Nov. 29, 2007, the contents of whichare hereby incorporated by reference.

BACKGROUND

Described below is a method of radio cell performance monitoring and/orcontrol in broadband fixed radio access networks or broadband cellularmobile radio access networks according to the ETSI/BRAN standard, suchas Universal Terrestrial Radio Access Networks (UTRANs), or any othertype of wireless communication network according to the Wi-Fi or WLANstandard (e.g. Bluetooth, IEEE 802.11 or HiperLAN), the GSM/GPRSstandard or the UMTS standard. Thereby, continuously monitored userequipment positioning data and radio link parameters indicating thequality of service (QoS) of a wireless link between a base transceiverstation (BTS) located in a mobile radio cell of the wireless cellularnetwork and a mobile terminal (MT) connected to and being served by thebase transceiver station, such as e.g. thesignal-to-noise-plus-interference ratio (SINR), power class and biterror rate (BER) in uplink and/or downlink direction of the wirelesslink, may be used for radio cell performance monitoring and/or control.By tracking the current positions of all mobile terminals which areserved by the network, hereinafter also referred to as user equipment(UE), the network is able to support location-based services offered tothese mobile terminals.

A network management system with an integrated alarm signaling unit maybe used which has access to a base transceiver station's linkperformance monitoring system and/or location measurement unit (LMU),wherein the latter is used for measuring current UE positioninginformation signals that are transmitted from a standard mobile terminalor specific wireless user equipment via the air interface of a fixed ormobile radio access network (RAN) to a base transceiver station of thenetwork. The system is thereby founded upon (but not limited to) theexpectation that UE positioning features will become more accurate,reliable and common in the future and that UE positioning willeventually be “business as usual”.

Fourth generation mobile networks will allow end users to roam overdifferent network technologies, such as based on the UMTS, CDMA2000 andWi-Fi standard. These networks make it possible to determine thelocation of the mobile terminal, which can then be used by diverseservice applications to provide enhanced wireless services. Thereby,each mobile network technology has its own specific way to determine amobile terminal's location and to provide this information to the enduser or to a mobile application.

Getting to know the current position and eventually the current velocityof a moving mobile terminal, such as e.g. a mobile phone or personaldigital assistant (PDA), does not only mean for the user being providedwith valuable information, but is also necessary and useful for manyoperations during the connection setup of a wireless link. Cellulartelecommunication systems can be equipped to perform a number ofdifferent positioning methods to enable location services to cellularsubscribers. In the following, different methods for allowing UEpositioning in mobile radio systems and some well-chosen UE positioningsystems (such as e.g. Cell-ID, Ecell-ID, A-GPS, OTDOA-IPDL, UTDOA, RTDand ADOA) and application scenarios<A[applications|utilization]> shallat least briefly be mentioned.

The exact position of a mobile terminal is especially needed forselecting a base transceiver station<A[base station|base transceiverstation]> when establishing a wireless connection (resource management),executing a handover to another base transceiver station<A[basestation|base transceiver station]> during an existing wireless link usedfor transferring text messages, speech data, audio or video data via theair interface, performing a distance<A[distance|removal]>---------basedpower control, providing location-based services, network planning andQoS maintenance dependent on the current location of a mobile networksubscriber's mobile terminal or for calculating mobile communicationcharges (home zone, long-distance calls,<A[long-distance calls|telephonecalle|trunk calle]> etc.).

Aside from their physical methods of measurement and their<A[their|her]>accuracy, the different methods for detecting the current position of asubscriber's mobile terminal (MT) differ in the node of the underlyingmobile radio system at which wireless RF signals are measured and atwhich node the current position of this mobile terminal is calculated.In particular, these nodes may e.g. be base transceiver stations<A[basestations|base transceiver station]> or specific location measurementunits and location servers.

Today's UE positioning methods as known from the related art can beclassified into a variety of distinct patent classes: from mobiledialing systems (H04Q), data transfer (H04B), radio direction findingand navigation systems (G01S), security tasks (G08G/B), automotivetechnology (B60R, B61L) up to medicine (A).Applications<A[applications|utilization]> where a mobile radio system isused for transferring UE positioning data in combination with thesatellite-based Global Positioning System (GPS), however, cover aconsiderably larger field.

The most important UE positioning methods are described in “Stage 2Functional Specification of User Equipment (UE) Positioning in UTRAN”(3GPP TS 25.305, 3rd Generation Partnership Project) by the TechnicalSpecification Group Radio Access Network and, at least partially, in“The GSM System for Mobile Communications” (Cell & Sys., Palaiseau(France), 1992, ISBN 2-9507190-0-7) by M. Mouly and M. Pautet. At leastsome of them will be briefly described in the following sections.

A cellular mobile radio network<A[land mobile network|mobilecommunication network|mobile radio network]> typicallyconsists<A[consists|exists]> of a number of mobile radio cells whoserespective sizes are given by the radio coverage range of a basetransceiver station which is located in the center of the respectivecell<A[base station|base transceiver station]>. If this range issubdivided into sectors by directional antennas, these sectorsrespectively constitute a mobile radio cell. When a mobile terminal isswitched on, it dials into a mobile radio cell of the cellular networkwhich provides best reception quality. The mobile terminal therebyreceives a unique cell identifier (cell ID) via a mobile radio channeland uses these and other data (e.g. synchronization information) tocommunicate with the base transceiver station<A[base station|basetransceiver station]> of the mobile radio cell and to registeritself<A[itself|himself|herself]> in the respective cell. The cellidentifier for the mobile radio cell into which the mobile terminal isdialed is also sent to a data base such that the system knows at anytime over which base transceiver station(s) a mobile terminal can becalled and to which destination node an incomingcall<A[call|reputation]> has to be routed.

A relatively simple method for providing positioning information istherefore to use a cell-ID based positioning method which uses a cellidentifier referring to the mobile radio cell of the wireless cellularnetwork where the user equipment is currently located. As the positionsof the base transceiver stations<A[base stations|base transceiverstation]> are known to the mobile radio system, the current position ofthe mobile terminal can easily be determined by a cell identifier whichrefers to the cell where the user equipment is currently located. Moreprecisely, a description of the geographical area covered by the cellwhich is related to the cell-ID, also referred to as Geographical AreaInformation (GAI), is used to find out the current position of the UE.The GAI identifies the geographical area of the respective cell and isrepresented by a polygon. This implies that the location of a UE can bedetermined by identifying the mobile radio cells, or one of these cells,where the UE is currently located and by associating the identity of thecell or cells with the GAI. The position of the mobile terminal is hencedetermined with cell granularity. In case of a radio access network(RAN), the radio network controller (RNC) typically determines a 3-15corner polygon that defines the geographical extension of the cell. Thecorners of this polygon are given as latitude-longitude pairs in theWGS114 geographical reference system. However, the size of a cellstrongly varies due to the network planning, such that the accuracy ofthe position can lie between 100 meters in urban areas with highsubscriber density and up to <A[up to|until]> 35 kilometers inperipheral and rural areas. Furthermore, the mobile terminal may alsoreceive cell identifiers of neighboring cells via other wireless links,so as to be able, in case of a degradation<A[degradation|deterioration]>of reception quality in the current cell, to rapidly and without anyloss of data execute a handover to a base transceiver station of anadjacent mobile radio cell.

Enhanced cell-ID (Ecell-ID) positioning augments the Cell-ID positioningwith auxiliary information that narrows down the area which isdetermined by the cell polygon. The most useful method in the widebandcode division multiple access (W-CDMA) system is the round trip time(RTT) measurement. This measurement determines the travel time, back andforth, from the base transceiver station to the UE and back. Using thespeed of light, the distance from the known position of the basetransceiver station to the UE can be calculated, the distance defining acircular stripe around the base transceiver station where the UE islocated, wherein the thickness of this stripe is given by themeasurement uncertainty. The Ecell-ID method is obtained by noticingthat the UE is located both in the respective mobile radio cell and inthe circular stripe. Hence, the UE is located in the intersection ofthese two geographical regions.

If there is no precise positioning information available for acall<A[call|reputation]> setup, DE 199 44 007 A1 describes that a radiopaging signal is transmitted by the respective Mobile Switching Center(MSC) before establishing the connection. Based on the reply of themobile terminal, the serving base transceiver station<A[basestation|base transceiver station]> can be found and the call canprecisely be directed to the corresponding base transceiverstation<A[base station|base transceiver station]>.

DE 100 04 738 C1 uses a cell identifier to determine the pre-dial codeof a current local fixed network. This pre-dial code is automaticallyput before the dialed fixed network number without requiring anycooperation of the user. A mobile subscriber is thus enabled to call afixed network subscriber whose pre-dial code is not known to him thoughknowing his/her dial number.

An international pre-dial code and a network pre-dial code of the homenetwork are automatically selected in accordance with DE 197 11 096 A1and employed for the setup of a communication link if the mobileterminal finds out that it is located abroad.

Due to the dependency between the signal strength of a wireless RFsignal that is received from a mobile terminal located in a mobile radiocell of a wireless cellular network and thedistance<A[distance|removal]> of the receiving base transceiver stationto the respective mobile terminal, signal strength measurements<A[basestations|base transceiver station]> can lead to a more precise UEpositioning, which is due to the fact that the positions of the basetransceiver stations in the particular mobile radio cells are known.When the signal strength of a wireless RF signal received from a mobileterminal is measured, one ideally obtains (when assuming line-of-sightconnection) a circle around the location of the receiving basetransceiver station for a given set of all positions where a mobileterminal whose current position is searched can possibly be located,which is due to the unique relationship between the signal strength andthe distance<A[distance|removal]> of the mobile terminal to thereceiving base transceiver station<A[base station|base transceiverstation]>.

In DE 195 33 472 A1, signal strengths of wireless RF signals receivedfrom a mobile terminal are predicted by its serving base transceiverstation<A[base station|base transceiver station]> as well as by itsneighboring terminals and correlated with corresponding measurements ofthe respective mobile terminal. After that, a similarity measure iscalculated. Finally, a position is assigned to the mobile terminal wherethe correlation coefficient takes on its maximum value. As shown in DE102 32 177 B3, the computational effort of this procedure can bedecreased when the search space is restricted based on the minimumreceived signal strengths of the base transceiver stations<A[basestations|base transceiver station]>. The accuracy of the respectivelyapplied UE positioning method can be increased by using hybrid methodswhere e.g. the angle of bearing is additionally determined by using adirectional antenna (DE 101 61 594 A1).

Assisted GPS (A-GPS) positioning is an enhancement of the US militaryglobal positioning system (GPS). Thereby, GPS reference receivers whichare e.g. attached to a cellular communication system are used forcollecting assistance data which, when transmitted to GPS receivers interminals connected to the cellular communication system, enhances theperformance of the GPS terminal receivers. Typically, A-GPS accuracy canbecome as good as 10 meters. The accuracy becomes worse in dense urbanareas and indoors, where sensitivity is often not high enough fordetecting very weak signals from the GPS satellites.

In the time difference of arrival (TDOA) positioning method, thepropagation time of a wireless RF signal transmitted from a mobileterminal to a base transceiver station<A[base station|base transceiverstation]> is measured. This time is then converted into adistance<A[distance|removal]> by calculating the product of thepropagation time with the velocity of light. The problem is thereby toachieve an exact synchronization of transmitter and receiver, sincesmallest deviations in time may lead to considerable errors as to thedistance value. Although mobile terminal and base transceiver stationcan be synchronized with the GPS system time, this is relativelyexpensive, in particular as far as concerns the mobile terminal.

A quite good positioning accuracy of approximately 50 meters can beaccomplished by using the downlink time difference of arrival (OTDOA)positioning method, which refers to a positioning method that, similarto A-GPS, relies on measuring the observed time difference of arrival(OTDOA) of a mobile terminal's wirelessly transmitted signals that arereceived at the location measurement units (LMUs) of the correspondingbase transceiver station which is connected to the mobile terminal viathe air interface <A[base stations|base transceiver station]>. The LMUsmust either be synchronized (e.g. with GPS), or the time deviation hasto be calculated by using the LMUs for mutually measuring the timedifference, thereby knowing the distances of the LMUs from each other.The OTDOA-IPDL method thereby performs UE measurements of pilot signalstransmitted from several base transceiver stations. The measurementresults are signaled to the RNC, where a hyperbolic trilateration methodis used for calculating the position of a UE. In order to enhance thehearability of the radio base transceiver stations in the UE, there is apossibility to use idle periods in the downlink (IPDL) in order toattenuate the transmissions from the base transceiver station to whichthe UE is connected. This reduces the interference and hence enhancesthe hearability of other radio base transceiver stations. A tentativeadvantage with OTDOA-IPDL is that it theoretically provides a betterindoor coverage than does A-GPS.

Uplink time difference of arrival (UTDOA) is a positioning method whichis currently under standardization within the 3GPP organization. It iscomparable to A-GPS in that it relies on time difference of arrivalmeasurements. However, the UTDOA method uses BTS (or separate LMU)measurements of signals transmitted from the positioned UE. Thetransmitted signal is detected in a number of base transceiver stationsor LMUs, after which the measured results are signaled to a positioningnode where the position of the UE is determined by a trilaterationmethod. In order to be able to detect the time of arrival frommeasurements of opportunity from the UE, a reference signal first needsto be created in a master LMU or master BTS. This is done by decoding ofthe signal, followed by reconstruction of the chip stream which thenforms the reference signal. An advantage of UTDOA positioning is that itprovides a better indoor coverage than does A-GPS.

A further possibility for obtaining UE positioning information isoffered by the round trip delay (RTD) positioning method, which measuresthe time delay for the propagation of a wireless RF signal transmittedfrom the mobile terminal which is located in a mobile radio cell of thewireless cellular network to the corresponding base transceiver stationwhich serves the mobile terminal. This method can also be carried outwithout having a base transceiver station being synchronized to themobile terminal<A[base stations|base transceiver station]>. According tothis method, the time which is required by a wireless RF signaltransmitted by the mobile terminal to arrive at the base transceiverstation<A[base station base transceiver station]> and return back to themobile terminal is measured. Thereby, transit time within the basetransceiver station<A[base station base transceiver station]> and theprocessing time in the mobile terminal are estimated. Since these timesmay greatly differ, depending on the respective manufacturer, thismethod does not provide a high level of exactness.

Another approach for positioning user equipment in mobile radio cells ofa wireless cellular network is given by the angle difference of arrival(ADOA) technique, which is known as a method for determining the angleof arrival of an incoming electromagnetic wave received from a mobileterminal at the locations of base transceiver stations which areconnected to the mobile terminal via the air interface. When the angleof arrival is determined for at least two base transceiver stations, theposition of the mobile terminal is obtained as the intersection point oftwo straight lines. To execute this positioning method, directionalantennas (such as antenna arrays) are needed at which the phasedifference of the arriving wave at the individual antenna elements ismeasured. Thereby, an accuracy of less than 100 meters can be achieved.

As described above, there exist different technologies for determiningthe current location of a UE. And probably there are and will come otherUE positioning methods in the future. Aside therefrom, the Nokia NetActoperating support system provides diverse network control and managementfeatures linked to the UE location data. For example, NetAct is able totrace incoming calls, collect UE performance indicators and follow thelocation of a UE on the cell level, which actually are the basic networkoperating control functions.

SUMMARY

Unfortunately, reliable real-time RAN performance and functionalitycontrol on a cell level is relatively difficult and requires differentand complex solutions for antenna, cable and active units monitoring.Today, many users are complaining about situations where a malfunctionis detected only after some time when the network quality has alreadybeen deteriorated.

Moreover, there are a lot of unnecessary site visits due to false alarmswhich are initiated by antenna lines and active antenna line units incase of a deteriorated link quality.

An aspect is to provide for an easy solution which reliably solves theproblems mentioned above so as to reduce the need for a complex andexpensive hardware for performance monitoring.

A first exemplary embodiment is dedicated to a network management systemhaving access to a base transceiver station's link performancemonitoring system and location measurement unit, the latter being usedfor detecting current positioning information signals which aretransmitted from a standard mobile terminal or any other, specific typeof wireless user equipment via the air interface of a cellular wirelesscommunication network (e.g. a mobile network according to the ETSI/BRAN,GSM, UMTS, Wi-Fi, W-LAN or IEEE 802.11 standard) to a base transceiverstation of the network. Thereby, the network management system mayinclude an integrated alarm signaling unit which may be adapted togenerate a warning message or alarm signal if at least one continuouslymonitored radio link parameter indicating the quality of service inuplink and/or downlink direction of the current wireless linkestablished between the base transceiver station and the mobile terminalor wireless user equipment, when the latter is moving, becomes worsethan a predefined threshold value, and wherein the radio link parameteris derived from a current measurement of at least one positioninginformation signal transmitted from the mobile terminal or wireless userequipment to the base transceiver station.

the threshold value may e.g. indicate a specific value of thecorresponding radio link parameter in a fixed range around a certainposition of the mobile terminal or wireless user equipment in the mobileradio cell where the base transceiver station is located.

To be more precise, the alarm signaling unit may be adapted to generatethe warning message or alarm signal based on the result of a comparisonbetween a currently measured value of the continuously monitoredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located within a fixed range around apredefined, known position within the aforementioned mobile radio cell.

Alternatively, the alarm signaling unit may be adapted to generate thewarning message or alarm signal based on the result of a comparisonbetween a currently measured value of the continuously monitoredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located at a known position withinthe intersectional radio cell areas of at least two adjacent basetransceiver stations within the coverage range of the cellular wirelesscommunication network.

The described network management system may thereby include a storageunit with an integrated data base for recording and storing thepositioning information and the corresponding radio link parameter.

According to a further aspect of the first embodiment, the alarmsignaling unit may be adapted to generate different levels of a warningmessage or different levels of an alarm signal depending on themagnitude and/or algebraic sign of the difference between the measuredvalue of the currently detected radio link parameter and the storedvalue of the corresponding radio link parameter characterizing thequality of service of the wireless link between the base transceiverstation and the mobile terminal or wireless user equipment.

A second exemplary embodiment is dedicated to a base transceiver stationwhich hosts a network management system having access to the basetransceiver station's link performance monitoring system and locationmeasurement unit, the latter being used for detecting current userequipment positioning information signals which are transmitted from astandard mobile terminal or any other, specific type of wireless userequipment via the air interface of a cellular radio access network to abase transceiver station of the network. Thereby, the network managementsystem may include an integrated alarm signaling unit which may beadapted to generate a warning message or alarm signal if at least onecontinuously monitored radio link parameter indicating the quality ofservice in uplink and/or downlink direction of the current wireless linkestablished between the base transceiver station and the mobile terminalor wireless user equipment, when the latter is moving, becomes worsethan a predefined threshold value, and wherein the radio link parameteris derived from a current measurement of at least one positioninginformation signal transmitted from the mobile terminal or wireless userequipment to the base transceiver station.

Again, the threshold value may e.g. indicate a specific value of thecorresponding radio link parameter in a fixed range around a certainposition of the mobile terminal or wireless user equipment in the mobileradio cell in which the base transceiver station is located.

The alarm signaling unit may be adapted to generate the warning messageor alarm signal based on the result of a comparison between a currentlymeasured value of the continuously monitoredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located within a fixed range around apredefined, known position within the aforementioned mobile radio cell.

As an alternative thereto, the alarm signaling unit may be adapted togenerate the warning message or alarm signal based on the result of acomparison between a currently measured value of the continuouslymonitored signal-to-noise-plus-interference ratio and/or bit error rateof a positioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located at a known position withinthe intersectional radio cell areas of at least two adjacent basetransceiver stations within the coverage range of the cellular radioaccess network.

The described network management system of the base transceiver stationmay thereby include a storage unit with an integrated data base forrecording and storing the positioning information and the correspondingradio link parameter.

According to a further aspect of the second embodiment, the alarmsignaling unit may be adapted to generate different levels of a warningmessage or different levels of an alarm signal depending on themagnitude and/or algebraic sign of the difference between the measuredvalue of the currently detected radio link parameter and the storedvalue of the corresponding radio link parameter characterizing thequality of service of the wireless link between the base transceiverstation and the mobile terminal or wireless user equipment.

A third exemplary embodiment is dedicated to a radio network controllerfor controlling the data transfer between a number of mobile terminalsand base transceiver stations interconnected over the air interface of afixed or mobile cellular radio access network, the radio networkcontroller hosting a network management system having access to a basetransceiver station's link performance monitoring system and locationmeasurement unit, the latter being used for detecting current userequipment positioning information signals which are transmitted from astandard mobile terminal or any other, specific type of wireless userequipment via the air interface of the radio access network to a basetransceiver station of the network. Thereby, the network managementsystem may include an integrated alarm signaling unit which may beadapted to generate a warning message or alarm signal if at least onecontinuously monitored radio link parameter indicating the quality ofservice in uplink and/or downlink direction of the current wireless linkestablished between the base transceiver station and the mobile terminalor wireless user equipment, when the latter is moving, becomes worsethan a predefined threshold value, and wherein the radio link parameteris derived from a current measurement of at least one positioninginformation signal transmitted from the mobile terminal or wireless userequipment to the base transceiver station.

Again, the threshold value may e.g. indicate a specific value of thecorresponding radio link parameter in a fixed range around a certainposition of the mobile terminal or wireless user equipment in the mobileradio cell in which the base transceiver station is located.

The alarm signaling unit may be adapted to generate the warning messageor alarm signal based on the result of a comparison between a currentlymeasured value of the continuously monitoredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located within a fixed range around apredefined, known position within the aforementioned mobile radio cell.

As an alternative thereto, the alarm signaling unit may be adapted togenerate the warning message or alarm signal based on the result of acomparison between a currently measured value of the continuouslymonitored signal-to-noise-plus-interference ratio and/or bit error rateof a positioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located at a known position withinthe intersectional radio cell areas of at least two adjacent basetransceiver stations within the coverage range of the cellular radioaccess network.

The described network management system of the radio network controllermay thereby include a storage unit with an integrated data base forrecording and storing the positioning information and the correspondingradio link parameter.

According to a further aspect of the third embodiment, the alarmsignaling unit may be adapted to generate different levels of a warningmessage or different levels of an alarm signal depending on themagnitude and/or algebraic sign of the difference between the measuredvalue of the currently detected radio link parameter and the storedvalue of the corresponding radio link parameter characterizing thequality of service of the wireless link between the base transceiverstation and the mobile terminal or wireless user equipment.

A fourth exemplary embodiment is dedicated to a method for monitoringthe link performance of a wireless link between a base transceiverstation providing data of a requested location-based service and astandard mobile terminal or any other, specific type of wireless userequipment requesting this service and being connected to the basetransceiver station via the air interface of a cellular wirelesscommunication network (such as e.g. a mobile network according to theETSI/BRAN, GSM, UMTS, Wi-Fi, W-LAN or IEEE 802.11 standard). Thereby, awarning message or alarm signal may be generated if at least onecontinuously monitored and newly measured radio link parameterindicating the quality of service in uplink and/or downlink direction ofthe current wireless link established between the base transceiverstation and the mobile terminal or wireless user equipment, when thelatter is moving, becomes worse than a predefined threshold value, andwherein the radio link parameter is derived from a current measurementof at least one positioning information signal transmitted from themobile terminal or wireless user equipment to the base transceiverstation.

Again, the threshold value may e.g. indicate a specific value of thecorresponding radio link parameter in a fixed range around a certainposition of the mobile terminal or wireless user equipment in the mobileradio cell in which the base transceiver station is located.

In this connection, the warning message or alarm signal may be generatedbased on the result of a comparison between a currently measured valueof the continuously monitored and newly measuredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located within a fixed range around apredefined, known position within the aforementioned mobile radio cell.

Alternatively, the warning message or alarm signal may be generatedbased on the result of a comparison between a currently measured valueof the continuously monitored and newly measuredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located at a known position withinthe intersectional radio cell areas of at least two adjacent basetransceiver stations within the coverage range of the cellular wirelesscommunication network.

According to a further aspect of the fourth embodiment, different levelsof a warning message or different levels of an alarm signal may begenerated depending on the magnitude and/or algebraic sign of thedifference between the measured value of the currently detected radiolink parameter and the stored value of the corresponding radio linkparameter characterizing the quality of service of the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment.

A peculiarity of the method is that the network operator may transmit anantenna beam of a beacon type of signal from a base transceiver stationin direction to a (previously triangulated or predefined) known fixedposition (e.g. a building) within the coverage range of the cellularnetwork and follow performance changes which might occur when the mobileterminal or specific wireless user equipment is moving towards thisfixed position where the radio link parameter takes on a previouslymeasured, known reference value. Beam widths and beam directions of thebeacon signals should thereby be selected in such a way that basetransceiver stations of several mobile radio cells can use them at thesame time for monitoring the radio link parameters of a wireless linkbetween the mobile terminal or specific user equipment and therespective base transceiver station.

A fifth exemplary embodiment is dedicated to the use of a basetransceiver station's location measurement unit for gaining informationabout the quality of service in uplink and/or downlink direction of awireless link via the air interface of a cellular mobile radio networkbetween the base transceiver station and a mobile terminal or wirelessuser equipment connected to and being located in the same mobile radiocell as the base transceiver station. This may be achieved by measuringcurrent values of at least one detected radio link parameter indicatingthe signal-to-noise-plus-interference ratio and/or bit error rate of acontinuously monitored positioning information signal received from amobile terminal or user equipment and comparing these current parametervalues with at least one previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located within a fixed range around apredefined, known position within the aforementioned mobile radio cellor when being located at a known position within the intersectionalradio cell areas of at least two adjacent base transceiver stationswithin the coverage range of the cellular mobile radio network.

A sixth exemplary embodiment is dedicated to a computer program productfor monitoring the link performance of a wireless link between a basetransceiver station providing data of a requested location-based serviceand a standard mobile terminal or any other, specific type of wirelessuser equipment requesting this service and being connected to the basetransceiver station via the air interface of a cellular wirelesscommunication network (such as e.g. a mobile network according to theETSI/BRAN, GSM, UMTS, Wi-Fi, W-LAN or IEEE 802.11 standard) when beinginstalled and running on a network management system having access tothe base transceiver station's link performance monitoring system andlocation measurement unit. Thereby, a warning message or alarm signalmay be generated if at least one continuously monitored and newlymeasured radio link parameter indicating the quality of service inuplink and/or downlink direction of the current wireless linkestablished between the base transceiver station and the mobile terminalor wireless user equipment, when the latter is moving, becomes worsethan a predefined threshold value, and wherein the radio link parameteris derived from a current measurement of at least one positioninginformation signal transmitted from the mobile terminal or wireless userequipment to the base transceiver station.

Again, the threshold value may e.g. indicate a specific value of thecorresponding radio link parameter in a fixed range around a certainposition of the mobile terminal or wireless user equipment in the mobileradio cell in which the base transceiver station is located.

In this connection, the warning message or alarm signal may be generatedbased on the result of a comparison between a currently measured valueof the continuously monitored and newly measuredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for v mobile terminal orwireless user equipment when being located within a fixed range around apredefined, known position within the aforementioned mobile radio cell.

As an alternative thereto, the warning message or alarm signal may begenerated based on the result of a comparison between a currentlymeasured value of the continuously monitored and newly measuredsignal-to-noise-plus-interference ratio and/or bit error rate of apositioning information signal transmitted over the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of thecorresponding positioning information signal for the mobile terminal orwireless user equipment when being located at a known position withinthe intersectional radio cell areas of at least two adjacent basetransceiver stations within the coverage range of the cellular wirelesscommunication network.

According to a further aspect of the sixth embodiment, different levelsof a warning message or different levels of an alarm signal may begenerated depending on the magnitude and/or algebraic sign of thedifference between the measured value of the currently detected radiolink parameter and the stored value of the corresponding radio linkparameter characterizing the quality of service of the wireless linkbetween the base transceiver station and the mobile terminal or wirelessuser equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages will become more apparent andmore readily appreciated from the following description of exemplaryembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a block diagram of a distributed Universal Terrestrial RadioAccess Network (UTRAN) in which the method described below mayadvantageously be applied;

FIG. 2 is a block diagram of a general system for user equipmentpositioning within an UTRAN;

FIG. 3 is a block diagram illustrating a communication scenario forillustrating a location registering procedure in a public land mobilenetwork;

FIG. 4 is a block diagram illustrating a communication scenario forillustrating the call delivering procedure in such a public land mobilenetwork;

FIG. 5A is a block diagram illustrating an initial communicationscenario for a wireless signaling between a base transceiver station anda mobile terminal located in a mobile radio cell of a wireless cellularnetwork, wherein the mobile terminal is located at a defined position(in the following also referred to as “beacon spot”) within the mobileradio cell and wherein positioning information as contained in awirelessly received positioning information signal is recorded to thebase transceiver station of the respective cell along with measuredradio link parameters in uplink and/or downlink direction of thereceived positioning information signal;

FIG. 5B is a block diagram illustrating a further communication scenariofor a wireless signaling between the base transceiver station and themobile terminal, wherein the mobile terminal is moving and approachingto the beacon spot or to a location within a defined range around theabove-mentioned beacon spot and wherein the measured radio linkparameters are compared to the recorded ones when the receivedpositioning information indicates that the mobile terminal is currentlylocated within the beacon spot;

FIG. 5C is a block diagram illustrating a still further communicationscenario for a wireless signaling between the base transceiver stationand a wireless signaling equipment, wherein the wireless signalingequipment is located at a known fixed position within the intersectionalradio cell areas of at least two adjacent base transceiver stationswithin the coverage range of the cellular mobile radio network;

FIG. 6 is a block diagram of the system components as contained in abase transceiver station; and

FIGS. 7A-7C are a flowchart of a method for monitoring the linkperformance of a wireless link between a base transceiver stationproviding data of a requested location-based service and a standardmobile terminal or any other, specific type of wireless user equipmentrequesting this service and being connected to the base transceiverstation via the air interface of a cellular wireless network

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout.

FIG. 1 shows a schematic block diagram of a distributed network 10according to the Universal Terrestrial Radio Access Network (UTRAN)standard in the scope of which the method described below mayadvantageously be applied. Radio Network Controllers (RNC) 102 a, 102 bthereby perform the control of communication connections and networkresources respectively of a number of base transceiver stations and areresponsible to provide connections to a Core Network 100. RNCs 102 a and102 b are connected to “Node B's” 104 a-d, wherein one Node B includesone or more base transceiver stations 106. Each base transceiver station106 controls the UEs within its covered cell area. Due to theabove-mentioned distinction, the RNC may have various roles: Regardingthe network resources, RNC 102 b acts as a controlling RNC (C-RNC) whichis responsible for the control of resources of a part of the networkincluding a number of cells, each of which serving a plurality of UEs108. Regarding the communication connections, an RNC 102 a or 102 b actsas the serving RNC (S-RNC) for those connections which terminate in thatRNC. However, when a UE 108 moves during an ongoing session from a firstRNC 102 a, which is the S-RNC for the corresponding communicationconnection, to a neighboring RNC 102 b, the original RNC 102 a stillremains the S-RNC for this connection while the second RNC 102 b, whichis in control of the resources that this connection uses, is a drift RNC(D-RNC) that supports the S-RNC 11 a with the necessary radio resources;however, without any influence on the connection. Thus, the D-RNCcontrols at least one cell that is used in a radio connection controlledby a serving RNC and supplies the S-RNC with resources.

Thus, it is a problem, as previously described, that positioninginformation, that is only based on the cell-ID, is not accurate enoughand may hence imply disadvantages for services where a more exactlocation of the UEs is required.

Another problem is that an S-RNC cannot get sufficient positioninginformation of a UE that has roamed during an ongoing session to aD-RNC, which provides network resources for the UE, while the S-RNCstill controls the connection of the UE.

In order to better understand how location measurement units and RadioNetwork Controllers work, it is helpful to briefly describe thearchitecture of a Universal Terrestrial Radio Access Network (UTRAN).Although the content of this section mainly deals with 3^(rd) and 4^(th)generation wireless systems operated according to the Universal MobileTelecommunication System (UMTS) standard, it should be mentioned that itis also relevant to the Global System for Mobile Communication (GSM)standard.

FIG. 2 shows a general system for user equipment positioning within sucha UTRAN. A Node B (here referred to as a single base transceiver stationBTS) is a network element of UTRAN that may provide measurements forposition estimation, make measurements of radio signals and communicatethese measurements to the core network. A location measurement unit(LMU), on the other hand, is a dedicated positioning device that makesradio measurements to support at least one positioning method ortechnology. There are two classes of LMUs: “stand-alone LMUs” and“associated LMUs”. A stand-alone LMU is accessed exclusively via the airinterface, which means that there is no other connection from astand-alone LMU to any other network element. However, an associated LMUmay make use of the radio apparatus and antennas of its associated NodeB. Radio Network Controllers (RNCs) play an important role under theUMTS standard. They can be classified into “controlling RNCs” (CRNCs),“serving RNCs” (SRNCs) and “drift RNCs” (DRNCs):

-   -   CRNCs manage positioning-related resources, broadcast system        information, and request UE positioning related measurements        from its associated Node B's and LMUs. All positioning and        assistance measurements received by an LMU are supplied to a        particular CRNC associated with the LMU. Instructions concerning        the timing, the nature and any periodicity of these measurements        are either provided by the CRNC or are pre-administered in the        CRNC.    -   SRNCs request information from other RNCs, control the flow of        positioning requests, select the positioning method, provide UE        positioning assistance data, and coordinate and control the        overall UE positioning task. The SRNC, of course, also provides        CRNC functionality with respect to UE positioning for its        associated Node B's and LMUs.    -   A DRNC is an UTRAN element having an active link to the UE that        is being located. The DRNC also provides CRNC functionality with        respect to UE positioning for its associated Node B's and LMUs.

The Mobile Switching Centers (MSC) or Visitor Location Registers (VLR)as depicted in FIG. 2 have a functionality associated with usersubscription authorization and managing call-related (andnon-call-related) positioning requests of a Location Service (LCS). Theyalso perform handover algorithm functions and mobility management.Location-related services of the MSC/VLRs are related to charging andbilling, LCS coordination, location request, authorization and operationof LCS services offered by an LCS server.

A Gateway Mobile Location Center (GMLC) as depicted in FIG. 2 is thefirst node of a public land mobile network (PLMN) that is accessed by anexternal LCS client. It has the functionality required to support theLCS. As shown in FIG. 2, the GMLC may be connected to atelegeoinformatics server (TGS) which resides outside the core network.

Location management is a two-stage process that enables the network todiscover the current attachment point of the mobile user for calldelivery. The first stage is location registration (or location update).In this stage, the mobile terminal periodically notifies the network ofits new access point, allowing the network to authenticate the user andrevise the user's location profile. The second stage is call delivery.Thereby, the network is queried for the user location profile and thecurrent position of the mobile host is found. Current schemes forlocation management in public land mobile networks are based on atwo-level data hierarchy such that two types of network location database, the home location register (HLR) and the visitor location register(VLR), are involved in tracking a mobile terminal (MT). In general,there is an HLR for each network and a user is permanently associatedwith an HLR in his/her subscribed network. Information about each user,such as e.g. the types of services subscribed and location information,are stored in a user profile located at the HLR. The number of VLRs andtheir placements vary among networks. Each VLR stores the information ofthe MTs (downloaded from the HLR) visiting its associated area. Each VLRis associated with one or more Mobile Switching Centers (MSCs), while asignaling network assures the connection among MSC, HLR and VLR.Signaling System 7 (SS10) is the protocol used for signaling exchange,and the signaling network is referred to as the SS10 network. For PLMN,the location registration procedures update the location data bases (HLRand VLRs) and authenticate the MT when up-to-date location informationof an MT is available. The call delivery procedures locate the MT basedon the information available at the HLR and the VLRs when a call for aMT is initiated.

To correctly deliver calls, the network must keep track of the locationof the MT. The location information is stored in two types of data base,VLR and HLR. As the MT moves around the coverage area, the data storedin these data bases may no longer be accurate. To ensure that calls canbe delivered successfully, the location registration updating process isperformed. The MT initiates location registration when it reports itscurrent location to the network; this location update is performedwhenever the MT enters a new location area (LA). Each LA may consist ofa number of cells and all the base transceiver stations belonging to thesame LA are connected to the same MSC. All the base transceiver stationswithin the same LA broadcast the ID of its LA periodically. When the MTenters a LA, it compares its registered LA ID with the current broadcastLA ID; location update is triggered if the two IDs are different. If thenew LA belongs to the same VLR as the old LA, the record at the VLR isupdated to record the ID of the new LA. Otherwise, if the new LA belongsto a different VLR, a number of extra steps are required to register theMT at the new serving VLR, update the HLR to record the ID of the newserving VLR and deregister the MT at the old serving VLR.

FIG. 3 shows the location registration procedure when the MT moves to anew LA. The following is the ordered list of tasks that are performedduring location registration:

-   -   1. The MT enters a new LA and transmits a location update        message to the new BS.    -   2. The BTS forwards the location update message to the MSC        through a wired link, which launches a registration query to its        associated VLR.    -   3. The VLR updates its record on the location of the MT. If the        new LA belongs to a different VLR, the new VLR determines the        address of the HLR of the MT from its mobile identification        number (MIN). This is achieved by a table lookup procedure        called global title translation. The new VLR then sends a        location registration message to the HLR; otherwise, location        registration is complete.    -   4. The HLR performs the required procedures to authenticate the        MT and records the ID of the new serving VLR of the MT. The HLR        then sends a registration acknowledgment message to the new VLR.    -   5. The HLR sends a registration cancellation message to the old        VLR.    -   6. The old VLR removes the record of the MT and returns a        cancellation acknowledgment message to the HLR.

Two major steps are involved in call delivery: determining the servingVLR of the called MT, and locating the visiting cell of the called MT.Locating the serving VLR of the MT involves the following data baselookup procedure (see FIG. 4):

-   -   1. The calling MT sends a call initiation signal to the serving        MSC of the MT through a nearby BS.    -   2. The MSC determines the address of the HLR of the called MT by        global title translation and sends a location request message to        the HLR.    -   3. The HLR determines the serving VLR of the called MT and sends        a route request message to the VLR. This VLR then forwards the        message to the MSC serving the MT.    -   4. The MSC allocates a temporary identifier called temporary        location directory number (TLDN) to the MT and sends a reply to        the HLR together with the TLDN.    -   5. The HLR forwards this information to the MSC of the calling        MT.    -   6. The calling MSC requests a call set up to the called MSC        through the SS10 network.    -   7. The called MSC initiates a paging procedure within the        current LA of the MT, and the MT replies in order to receive the        call.

The procedure described above allows the network to set up a connectionfrom the calling MT to the serving MSC of the called MT. Since each MSCis associated with a LA, and there is more than one cell in each LA istherefore necessary to determine the cell location of the called MT.This is accomplished by a paging procedure such that polling signals arebroadcasted to all cells within the residing LA of the called MT. Onreceiving the polling signal, the MT sends a reply, which allows the MSCto determine its current residing cell.

FIG. 5A shows an initial communication scenario for a wireless signalingbetween a base transceiver station and a mobile terminal located in amobile radio cell of a wireless cellular network. In this communicationscenario, the mobile terminal is located at a defined position (in thefollowing also referred to as “beacon spot”) within the mobile radiocell. A wireless RF signal which is used for carrying positioninginformation indicating the current location of the mobile terminal istransmitted to the base transceiver station of the corresponding mobileradio cell. In the base transceiver station, where the RF signal iswirelessly received, the positioning information is stored in anintegrated data base along with measured radio link parameters(signal-to-noise-plus-interference ratio, bit error rate, etc.) whichare derived from the received positioning information signal. Theseradio link parameters thereby indicate the quality of service of therespective wireless link between the mobile terminal and the basetransceiver station in uplink and/or downlink direction.

In FIG. 5B, a further communication scenario for a wireless signalingbetween the base transceiver station and the mobile terminal is shown.Therein, the mobile terminal is moving and approaching to the beaconspot or to a location within a defined range around the beacon spot. Thedepicted scenario shows that currently measured radio link parametersindicating the quality of service of the respective wireless linkbetween the mobile terminal and the base transceiver station arecompared with corresponding radio link parameters which have previouslybeen recorded for the mobile terminal when the received positioninginformation indicates that the respective mobile terminal is currentlylocated within the beacon spot.

FIG. 5 c finally shows a still further communication scenario for awireless signaling between the base transceiver station and a wirelesssignaling equipment. In contrast to the communication scenariosdescribed above, the wireless signaling equipment may e.g. be located ata known fixed position within the intersectional radio cell areas of atleast two adjacent base transceiver stations within the coverage rangeof the cellular mobile radio network. At this position, all measuredradio link parameter take on previously measured, known referencevalues. Accordingly, wireless positioning information signals which arereceived at any one of these base transceiver stations may be used forradio network performance monitoring. This may e.g. be done in that anetwork operator may transmit an antenna beam of a beacon type of signalfrom a base transceiver station in direction to the known fixed positionand follow performance changes which might occur when the mobileterminal MT or specific wireless user equipment UE is moving towards oraway from this fixed position. Beam widths and beam directions of thebeacon signals should thereby be selected in such a way that basetransceiver stations of several mobile radio cells can use them at thesame time for monitoring the radio link parameters of a wireless linkbetween the mobile terminal or specific user equipment and therespective base transceiver station, which has also been mentionedabove.

A schematic block diagram of the system components as contained in abase transceiver station BTS is depicted in FIG. 6. the base transceiverstation thereby includes a network management system NMS having accessto the base transceiver station's link performance monitoring systemLPMS and location measurement unit LMU, wherein the latter, as describedabove, is used for detecting current positioning information signalswhich are received from a standard mobile terminal MT or any other,specific type of wireless user equipment UE via the air interface of awireless communication network, wherein the network may e.g. be given bya mobile network according to the ETSI/BRAN, GSM, UMTS, Wi-Fi, W-LAN orIEEE 802.11 standard. The depicted network management system is furtherequipped with an integrated alarm signaling unit ASU which may beadapted to generate a warning message or alarm signal if at least onecontinuously monitored radio link parameter indicating the quality ofservice (QoS) in uplink and/or downlink direction of the currentwireless link established between the base transceiver station BTS andthe mobile terminal MT or wireless user equipment UE, when the latter ismoving, becomes worse than a predefined threshold value or previouslymeasured, known radio link parameter stored in a BTS-site data base DB.As described above, the radio link parameter is derived from a currentmeasurement of at least one positioning information signal transmittedfrom the mobile terminal MT or wireless user equipment UE to the basetransceiver station BTS. The above-described comparison of the currentlymeasured radio link parameter and the stored value of the correspondingradio link parameter is done by the processor of a controller CTR whichis connected to the alarm signaling unit ASU via control data outputinterface IF.

FIG. 7 shows a three-part flow chart which illustrates theabove-described method. After having established (S0) a wireless linkbetween a base transceiver station BTS and a standard mobile terminal MTor any other, specific type of wireless user equipment UE beingconnected to the base transceiver station via the air interface of acellular wireless communication network (such as e.g. a mobile networkaccording to the ETSI/BRAN, GSM, UMTS, Wi-Fi, W-LAN or IEEE 802.11standard) and having received (S1) an NMS-initiated request for awireless positioning information signal from the mobile terminal MT orspecific wireless user equipment UE, a positioning information signalindicating the position of the mobile terminal MT or wireless userequipment UE is wirelessly transmitted (S2) via the air interface of thecellular wireless communication network to the base transceiver stationBTS. The link performance monitoring system LPMS of the base transceiverstation BTS then measures (S3) at least one uplink radio parameterindicating the quality of service of the wireless link from the receivedpositioning information signal. After that, a reference scenario asgiven by the BTS communicating with the MT or wireless UE when beinglocated at a known geographical position (“beacon spot”) within themobile radio cell is defined, thereby recording (S4 a) the received userpositioning information and storing (S4 b) them together with themeasured radio link parameters indicating the quality of the wirelesslink in a data base DB which is located at the BTS site. After havingreceived (S5) an NMS-initiated request for a wireless positioninginformation signal from the mobile terminal MT or wireless userequipment UE, the mobile terminal MT or wireless user equipment UEwirelessly transmits (S6) new positioning information to the basetransceiver station BTS which may e.g. indicate a movement of the mobileterminal MT or wireless user equipment UE. The current positioninginformation is then compared (S7) with the recorded positioninginformation which is stored in the data base. The base transceiverstation thereby continuously monitors (S8 a) and newly measures (S8 b)the same radio link parameter(s) indicating the quality of service (QoS)in uplink and/or downlink direction of the current wireless link betweenthe base transceiver station BTS and the mobile terminal MT or wirelessuser equipment UE. If the mobile terminal MT or wireless user equipmentUE is located in the beacon spot, which is determined by the query inS9, and if the newly measured radio link parameter(s) are worse thanstored value of the corresponding radio link parameter(s) when beingused as a threshold, which is asked in query S10, alarm signaling unitASU generates (S11) a warning message or alarm signal. Otherwise, theprocedure is again continued with S5. In case the wireless link does notprovide a guaranteed quality of service within a given period of time,proper actions set by the network management system NMS are taken. Forexample, a handover procedure for executing a handover to another basetransceiver station may be initiated (S12 a), and the existing wirelesslink may be disconnected (S12 b).

Practical examples of frequently offered location-based services in thescope of which the method described above can advantageously be appliedare e.g. location-based services which are used for providing emergencyinformation for a district (e.g. closing of a park, fire alarms, warningof dangers), for advertising (inauguration of a new shop, announcementfor the beginning of an event in a few minutes), for triggering aservice if the user enters a specific area (e.g. offering of specificinformation therefor), for changing to a better (or cheaper) type ofconnection link (such as e.g. W-LAN, Bluetooth etc.) or for triggering aservice, if the user stays at the same place for a certain period oftime (e.g. when queuing at a cash desk or in front of <A[in frontof|before]> an entrance, when regarding a display or poster, waiting ata bus stop, etc.). Other examples of application may be informing theuser when approaching to a specific place, e.g. a restaurant or a hotel,informing the user when approaching to a specific other user (such ase.g. a friend, a job<A[job|work]> colleague, another player of a gamethe user is involved, etc.) or to a specific appliance (such as e.g. aparking ticket automat), informing the user, if a person or applianceleaves a certain area (theft protection system, child leaves party,etc.), location-dependent accounting of call charges (in particular, thesubscriber must be informed that the accounting of call charges changesif he/she leaves or enters a certain area) as well as statisticalevaluations (such as e.g. determining the number of mobile devices in acertain area for better recognition of a traffic jam or reacting to theraised demand for public transport after the end of a mass event, suchas e.g. a concert, sport event etc.). Location-based service informationcan also be broadcasted within a cell such that all mobile terminalswhich are located in this cell can receive this information. Themechanisms of the location-based services are specified in “LocationServices (LCS). Service Description. Stage 1” (3GPP TS 22.071, 3rdGeneration Partnership Project) and “Functional Stage 2: Description ofLocation Services (LCS)” (3GPP TS 23.271, 3rd Generation PartnershipProject) by the Technical Specification Group Services and SystemAspects. Basically a so-called “LCS client” (e.g. a software unit in themobile terminal or in the net) requires accordingly a location-dependentservice at a “LCS server”, that determines the position of the mobileterminal then and provides the corresponding service the enquiring “LCSclient”.

While the present invention has been illustrated and described in detailin the drawings and in the foregoing description, such illustration anddescription are to be considered illustrative or exemplary and notrestrictive, which means that the invention is not limited to thedisclosed embodiments. Other variations to the disclosed embodiments canbe understood and effected by those skilled in the art in practicing themethod, from a study of the drawings and the text of the disclosure. Inthe claims, a single processor or other unit may fulfill the functionsof several items recited in the claims. The mere fact that certainmeasures are recited in mutually different dependent claims does notindicate that a combination of these measures can not be used toadvantage. A computer program may be stored/distributed on a suitablemedium, such as an optical storage medium or a solid-state mediumsupplied together with or as part of other hardware, but may also bedistributed in other forms, such as e.g. via the Internet or other wiredor wireless telecommunication systems. The system can output the resultsto a display device, printer, readily accessible memory or anothercomputer on a network.

A description has been provided with particular reference to exemplaryembodiments thereof and examples, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the claims which may include the phrase “at least one of A, B and C”as an alternative expression that means one or more of A, B and C may beused, contrary to the holding in Superguide v. DIRECTV, 358 F3d 870, 69USPQ2d 1865 (Fed. Cir. 2004).

1. A network management system having access to a link performancemonitoring system and a location measurement unit, both of a basetransceiver station, the location measurement unit being used fordetecting current positioning information signals which are transmittedfrom user equipment via a wireless interface of a cellular wirelesscommunication network to the base transceiver station of the cellularwireless communication network, said network management systemcomprising: an integrated alarm signaling unit generating a warningmessage or alarm signal if at least one continuously monitored radiolink parameter indicating quality of service in uplink and/or downlinkdirection of a current wireless link established between the basetransceiver station and the user equipment, when the user equipment ismoving, becomes worse than a predefined threshold value, and the atleast one continuously monitored radio link parameter is derived from acurrent measurement of at least one positioning information signaltransmitted from the user equipment to the base transceiver station. 2.The network management system according to claim 1, wherein thepredefined threshold value indicates a specific value of a correspondingradio link parameter in a fixed range around a certain position of theuser equipment in a mobile radio cell in which the base transceiverstation is located.
 3. The network management system according to claim2, wherein said integrated alarm signaling unit generates the warningmessage or the alarm signal based on a result of a comparison between acurrently measured value of a continuously monitoredsignal-to-noise-plus-interference ratio and/or a bit error rate of apositioning information signal transmitted over the current wirelesslink between the base transceiver station and the user equipment and apreviously measured, stored value of the corresponding radio linkparameter which indicates the signal-to-noise-plus-interference ratioand/or the bit error rate of a corresponding positioning informationsignal for the user equipment when being located within a fixed rangearound a predefined, known position within the mobile radio cell.
 4. Thenetwork management system according to claim 2, wherein said integratedalarm signaling unit generates the warning message or the alarm signalbased on a result of a comparison between a currently measured value ofa continuously monitored signal-to-noise-plus-interference ratio and/ora bit error rate of a positioning information signal transmitted overthe current wireless link between the base transceiver station and theuser equipment and a previously measured, stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or the bit error rate of acorresponding positioning information signal for the user equipment whenbeing located at a known position within intersectional radio cell areasof at least two adjacent base transceiver stations within a coveragerange of the cellular wireless communication network.
 5. The networkmanagement system according to claim 4, further comprising a storageunit with an integrated database recording and storing positioninginformation and the corresponding radio link parameter.
 6. The networkmanagement system according to claim 5, wherein said alarm signalingunit generates different levels of a warning message or different levelsof an alarm signal depending on a magnitude and/or algebraic sign of adifference between the currently measured value of the at least onecontinuously monitored radio link parameter and the stored value of thecorresponding radio link parameter indicating the quality of service ofthe current wireless link between the base transceiver station and theuser equipment.
 7. A base transceiver station which hosts a networkmanagement system having access to a link performance monitoring systemand a location measurement unit, both of the base transceiver station,the location measurement unit detecting current user equipmentpositioning information signals which are transmitted from userequipment via a wireless interface of a cellular radio access network tosaid base transceiver station, comprising: an integrated alarm signalingunit generating a warning message or an alarm signal if at least onecontinuously monitored radio link parameter indicating quality ofservice in uplink and/or downlink direction of a current wireless linkestablished between said base transceiver station and the userequipment, when the user equipment is moving, becomes worse than apredefined threshold value, where the at least one continuouslymonitored radio link parameter is derived from a current measurement ofat least one positioning information signal transmitted from the userequipment to said base transceiver station.
 8. The base transceiverstation according to claim 7, wherein the predefined threshold valueindicates a specific value of a corresponding radio link parameter in afixed range around a certain position of the user equipment in a mobileradio cell in which said base transceiver station is located.
 9. Thebase transceiver station according to claim 8, wherein said alarmsignaling unit generates the warning message or the alarm signal basedon a result of a comparison between a currently measured value of acontinuously monitored signal-to-noise-plus-interference ratio and/or abit error rate of a positioning information signal transmitted over thecurrent wireless link between said base transceiver station and the userequipment and a previously measured, stored value of the correspondingradio link parameter which indicates the continuously monitoredsignal-to-noise-plus-interference ratio and/or the bit error rate of acorresponding positioning information signal for the user equipment whenlocated within a fixed range around a predefined, known position withina mobile radio cell.
 10. The base transceiver station according to claim8, wherein said alarm signaling unit generates the warning message orthe alarm signal based on a result of a comparison between a currentlymeasured value of a continuously monitoredsignal-to-noise-plus-interference ratio and/or a bit error rate of apositioning information signal transmitted over the wireless linkbetween said base transceiver station and the user equipment and apreviously measured, stored value of the corresponding radio linkparameter which indicates the continuously monitoredsignal-to-noise-plus-interference ratio and/or a bit error rate of acorresponding positioning information signal for the user equipment whenlocated at a known position within intersectional radio cell areas of atleast two adjacent base transceiver stations within a coverage range ofa cellular radio access network.
 11. The base transceiver stationaccording to claim 10, further comprising a storage unit with anintegrated database for recording and storing positioning informationand the corresponding radio link parameter.
 12. The base transceiverstation according to claim 11, wherein said alarm signaling unitgenerates different levels of a warning message or different levels ofan alarm signal depending on a magnitude and/or an algebraic sign of adifference between the currently measured value of the at least onecontinuously monitored radio link parameter and the stored value of thecorresponding radio link parameter characterizing quality of service ofthe current wireless link between said base transceiver station and theuser equipment.
 13. A radio network controller for controlling datatransfer between mobile terminals and base transceiver stationsinterconnected over a wireless interface of a radio access network whichis fixed or mobile cellular, said radio network controller hosting anetwork management system having access to a link performance monitoringsystem and a location measurement unit, both of a base transceiverstation, the location measurement unit detecting current user equipmentpositioning information signals which are transmitted from userequipment via a wireless interface of the radio access network to one ofthe base transceiver stations of the radio access network, said radionetwork controller comprising: an integrated alarm signaling unitgenerating a warning message or an alarm signal if at least onecontinuously monitored radio link parameter indicating quality ofservice in uplink and/or downlink direction of a current wireless linkestablished between the one of the base transceiver stations and theuser equipment, when the user equipment is moving, becomes worse than apredefined threshold value, and the at least one continuously monitoredradio link parameter is derived from a current measurement of at leastone positioning information signal transmitted from the user equipmentto the one of the base transceiver stations.
 14. The radio networkcontroller according to claim 13, wherein the predefined threshold valueindicates a specific value of a corresponding radio link parameter in afixed range around a certain position of the user equipment in a mobileradio cell in which the one of the base transceiver stations is located.15. The radio network controller according to claim 14, wherein saidintegrated alarm signaling unit generates the warning message or thealarm signal based on a result of a comparison between a currentlymeasured value of the continuously monitoredsignal-to-noise-plus-interference ratio and/or a bit error rate of theat least one positioning information signal and a previously measured,stored value of the corresponding radio link parameter which indicatesthe continuously monitored signal-to-noise-plus-interference ratioand/or a bit error rate of a corresponding positioning informationsignal for the user equipment when located within a fixed range around apredefined, known position within the mobile radio cell.
 16. The radionetwork controller according to claim 14, wherein said alarm signalingunit generates the warning message or the alarm signal based on a resultof a comparison between a currently measured value of the continuouslymonitored signal-to-noise-plus-interference ratio and/or a bit errorrate of a positioning information signal transmitted over the wirelesslink between the one of the base transceiver stations and the userequipment and a previously measured, stored value of a correspondingpositioning information signal which indicates the continuouslymonitored signal-to-noise-plus-interference ratio and/or a bit errorrate of a corresponding positioning information signal for the userequipment when located at a known position within intersectional radiocell areas of at least two adjacent base transceiver stations within acoverage range of a cellular radio access network.
 17. The radio networkcontroller according to claim 16, wherein the network management systemincludes a storage unit with an integrated database for recording andstoring positioning information and the corresponding radio linkparameter.
 18. The radio network controller according to claim 17,wherein said alarm signaling unit generates different levels of awarning message or different levels of an alarm signal depending on amagnitude and/or an algebraic sign of a difference between a currentlymeasured value of the at least one continuously monitored radio linkparameter and the stored value of the corresponding radio link parameterindicating the quality of service of the current wireless link betweenthe one of the base transceiver stations and the user equipment.
 19. Amethod for monitoring the link performance of a wireless link betweenuser equipment and a base transceiver station providing data of alocation-based service requested by the user equipment requesting whichis connected to the base transceiver station via a wireless interface ofa cellular wireless communication network, comprising: generating awarning message or an alarm signal if at least one continuouslymonitored and newly measured radio link parameter indicating quality ofservice in uplink and/or downlink direction of a current wireless linkestablished between the base transceiver station and the user equipment,when the user equipment is moving, becomes worse than a predefinedthreshold value, and where the newly measured radio link parameter isderived from a current measurement of at least one positioninginformation signal transmitted from the user equipment to the basetransceiver station.
 20. The method according to claim 19, wherein thepredefined threshold value indicates a specific value of a correspondingradio link parameter in a fixed range around a certain position of theuser equipment in a mobile radio cell in which the base transceiverstation is located.
 21. The method according to claim 20, wherein thewarning message or the alarm signal is generated based on a result of acomparison between a currently measured value of a continuouslymonitored and newly measured signal-to-noise-plus-interference ratioand/or a bit error rate of a positioning information signal transmittedover the current wireless link between the base transceiver station andthe user equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or the bit error rate of acorresponding positioning information signal for the user equipment whenlocated within a fixed range around a predefined, known position withinthe mobile radio cell.
 22. The method according to claim 20, wherein thewarning message or the alarm signal is generated based on a result of acomparison between a currently measured value of a continuouslymonitored and newly measured signal-to-noise-plus-interference ratioand/or a bit error rate of a positioning information signal transmittedover the current wireless link between the base transceiver station andthe user equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or the bit error rate of acorresponding positioning information signal for the user equipment whenlocated at a known position within intersectional radio cell areas of atleast two adjacent base transceiver stations within a coverage range ofthe cellular wireless communication network.
 23. The method according toclaim 22, wherein different levels of the warning message or differentlevels of the alarm signal are generated depending on a magnitude and/oran algebraic sign of a difference between the currently measured valueof the continuously monitored and newly measured radio link parameterand the stored value of the corresponding radio link parameterindicating the quality of service of the current wireless link betweenthe base transceiver station and the user equipment.
 24. A method ofusing a location measurement unit of a base transceiver station forgaining information about quality of service in uplink and/or downlinkdirection of a wireless link via a wireless interface of a cellularmobile radio network between the base transceiver station and userequipment connected to and located in a same mobile radio cell as thebase transceiver station, comprising: measuring current values of atleast one detected radio link parameter indicating asignal-to-noise-plus-interference ratio and/or a bit error rate of acontinuously monitored positioning information signal received from theuser equipment; and comparing the current values of the at least onedetected radio link parameter with at least one previously measured andstored value of a corresponding radio link parameter which indicates asignal-to-noise-plus-interference ratio and/or a bit error rate of acorresponding positioning information signal for the user equipment whenlocated within a fixed range around a predefined, known position withinthe same mobile radio cell or when located at a known position withinintersectional radio cell areas of at least two adjacent basetransceiver stations within a coverage range of the cellular mobileradio network.
 25. A computer-readable medium encoded with a computerprogram that when exected by at least one processor causes the at leastone processor to perform a method of monitoring link performance of awireless link between user equipment and a base transceiver stationproviding data of a location-based service requested by the userequipment which is connected to the base transceiver station via awireless interface of a cellular wireless communication network wheninstalled and running on a network management system having access to alink performance monitoring system and location measurement unit, bothof the base transceiver station, said method comprising: generating awarning message or an alarm signal if at least one continuouslymonitored and newly measured radio link parameter indicating quality ofservice in uplink and/or downlink direction of a current wireless linkestablished between the base transceiver station and the user equipment,when the user equipment is moving, becomes worse than a predefinedthreshold value, and wherein the radio link parameter is derived from acurrent measurement of at least one positioning information signaltransmitted from the user equipment to the base transceiver station. 26.The computer-readable medium according to claim 25, wherein thepredefined threshold value indicates a specific value of a correspondingradio link parameter in a fixed range around a certain position of theuser equipment in a mobile radio cell in which the base transceiverstation is located.
 27. The computer-readable medium according to claim26, wherein the warning message or the alarm signal is generated basedon a result of a comparison between a currently measured value of thecontinuously monitored and newly measuredsignal-to-noise-plus-interference ratio and/or a bit error rate of apositioning information signal transmitted over the current wirelesslink between the base transceiver station and the user equipment and apreviously measured and stored value of the corresponding radio linkparameter which indicates a signal-to-noise-plus-interference ratioand/or a bit error rate of a corresponding positioning informationsignal for the user equipment when located within a fixed range around apredefined, known position within the mobile radio cell.
 28. Thecomputer-readable medium according to claim 26, wherein the warningmessage or the alarm signal is generated based on a result of acomparison between a currently measured value of the continuouslymonitored and newly measured signal-to-noise-plus-interference ratioand/or a bit error rate of a positioning information signal transmittedover the current wireless link between the base transceiver station andthe user equipment and a previously measured and stored value of thecorresponding radio link parameter which indicates thesignal-to-noise-plus-interference ratio and/or bit error rate of acorresponding positioning information signal for the user equipment whenbeing located at a known position within intersectional radio cell areasof at least two adjacent base transceiver stations within a coveragerange of the cellular wireless communication network.
 29. Thecomputer-readable medium according to claim 28, wherein different levelsof a warning message or different levels of an alarm signal aregenerated depending on a magnitude and/or an algebraic sign of adifference between the currently measured value of the continuouslymonitored and newly measured radio link parameter and the stored valueof the corresponding radio link parameter indicating the quality ofservice of the current wireless link between the base transceiverstation and the user equipment.